Surface running props

[skialot2]

Does anyone have any opinions on a Turbo TXP OT-4? They are supposed to be good for very high mounted engines on lightweight go fast boats, have very good grip and very good control. They are over and thru hub. But, for some reason, they make both a vented and unvented version. I found them brand new for $547+ shipping, with the hub. $20 more for the vented version. Has anyone used them? Got an opinion?

[David - WI]

If it's just opinions... you gotta figure out what you have before you buy anything else. There's something wrong with the numbers you have.

[OnPad]

It was hard for me estimate the rpm from Skialot's video, but it sounded like it was revving pretty good. The water conditions didn't look the best for running top end numbers.

Here's a little blurb about slip on a model boat site I use. It's slightly higher than what I've seen on my boats.


Every prop is going to be different, and the faster the boat runs (less wetted surface), the more efficient the propeller will work. Only the very best of setups on my fastest boats, run low teens, alot of props are closer to 20 percent. I can get the slip numbers down a little by lowering the engine's, but they aren't usually as fast.
I would find it more odd to be in the single digits for slip numbers in a v hull doing freeway speeds. Maybe a ultralight at 100+mph it would be more conceivable.

I will still guess 28, or 30p for the best top speed on Skialot's boat. Probably 27-28p with four blades. Or 28-30p in a 3 blade.
No good can come from being over propped, it will slow the boat down, and make heat. Been there, done that.

[allstock]

No way that tach is accurate, doesn't sound like over 5-5500 rpm to me, if that.

[OnPad]

No way that tach is accurate, doesn't sound like over 5-5500 rpm to me, if that.

He's running a 26p Chopper, which I happen to have a couple of. If I was spinning the rpm you suggest, with said prop, I would be going 50 -55mph. My boats spin a 26p v6 chopper near 7000rpm. My Bullet basser is lucky to see 70mph, and my LTV runs about 75mph with a 26p v6 chopper.

[skialot2]

My 26P Chopper has been worked up to a 30P. I know it's hard to believe. But it runs exactly the same RPM as a brand new Hill 30P signature chopper. I have been playing with a prop slip calculator. Assuming I am correct, if I put in the parameters from when I had this prop on my Glastron with a 135. 30P - 2.0 ratio - 5500 RPM - 58 MPH Then click on calculate for propeller slip, It say 26% slip. If I change the gear ratio to 1.87 and the actual speed to GPS confirmed 68 MPH. Then click on calculate RPM, it says 6049 RPM. I think my tach is off by about 1000 RPM. That would explain everything. It would put the slip percentage right in line with OnPads post about deep vee prop slip %.

I am going to buy a cheap inductive tach from eBay to test it with. I found one with a MAX RPM recall.

[OnPad]

The little blurb about the model boat prop calculator I posted, probably wasn't the most accurate representation, when compared to full size boats. The little boats use 2 blade props. When you start adding blades the slip goes down some. Most 3 blades run 16-20% on my real boats, and full diameter 4 blades are in the mid to low teens. Any who, I wouldn't get too hung up on slip numbers, they change with a flick of the jackplate switch, or the speed your going.

Your tack should have the option to read 12 poles, in order to work properly with your v6 Merc. Marine tach is a specialized deal, most automotive tachs wont work right with a stator.

[David]

The Turbo props did well in Bass & Walleye Boat testing forever ago. I don’t know anyone using one

[AlliStan]

I have a rare to find, original Spinelli star 4 14.5 X 28.5 small shaft I can sell you. Still in like new condition.
Has great lift and holding power and very fast top end speed.

Do you have any pics of that prop?

You can contact me at stanhillis@gmail.com.

Thanks, Stan

[skialot2]

Suspicion confirmed!!! Tachometer is off by a hundred or two at idol and about 1400-1500 RPMs at full throttle. I installed a tachometer for small engines. Inductive wire wraps around the spark plug wire and it counts ignition fires. Good for up to 10K RPM. Supposed to be accurate within 10RPM. Has max RPM recall. Also has an hour meter, service reminders and other crap I will never use. Says I had a max RPM of 5640. I guess I am going to buy a new tach for the boat. If that confirms the RPM, I will get about a 28 pitch prop.

[RiverJunkie702]

My 26P Chopper has been worked up to a 30P. I know it's hard to believe. But it runs exactly the same RPM as a brand new Hill 30P signature chopper. I have been playing with a prop slip calculator. Assuming I am correct, if I put in the parameters from when I had this prop on my Glastron with a 135. 30P - 2.0 ratio - 5500 RPM - 58 MPH Then click on calculate for propeller slip, It say 26% slip. If I change the gear ratio to 1.87 and the actual speed to GPS confirmed 68 MPH. Then click on calculate RPM, it says 6049 RPM. I think my tach is off by about 1000 RPM. That would explain everything. It would put the slip percentage right in line with OnPads post about deep vee prop slip %.

I am going to buy a cheap inductive tach from eBay to test it with. I found one with a MAX RPM recall.

A 26 pitch prop cannot be reworked to a 30 pitch! Unless you cut the blades off and welded Them back on at 30 pitch. Just can’t be done, 2 inches either way up or down is the max. Even then that’s just tweaking the Blades outer 30%. You can’t change the pitch at the root of the blade. some manufacturers are more aggressive with the progression of pitch. With a pitch gauge several props to measure you see one manufactures 26 pitch vary quite a bit from another manufacturer 26 pitch from leading edge to trailing edge. Anyways just saying you can’t change a 26 to a 30 pitch.

[skialot2]

I totally agree with you. 2" up or down max. Down is supposed to be easier. That is the conventional wisdom. But, real world experience is telling me different. My prop is a Quicksilver Chopper 48 89858 A-4 26P, that was reworked by someone before I bought it from eBay. When I was using it on my Glastron with my 135 it ran 5500RPM's. (No LWP. 2 top holes plugged. Ran 3" below keel. No pad) It ran fine. But I noticed one blade had a couple minor bends on the face. I called Hill Marine to have it reconditioned. When I told Ron the prop was already probably labbed, he said you never know what someone else did to it. Then suggested I buy one of their Signature Choppers. So, I did. I ordered a 28P Chopper 3. It ran 400 RPM higher on 5 MPH slower. So I sent it back and exchanged it for a 30 Pitch. That 30P prop ran the same 5500 RPM, but still 2 MPH slower as the labbed 26 chopper. When I switched to my Checkmate with the 150, it ran 5600 with the Hill Chopper until I lost it when the mid section broke. When I fixed the 150. It ran 5600 with the Quicksilver Chopper. That is why I say this 26P prop has been reworked to a 30P.

[skialot2]

Picked up a Mazco RE4 27P the other day. An old one with a pressed in rubber hub. It looked like it was pretty beat up. Like it has been worked and reworked. Probably a 5 maybe a 6 on S&F scale. He said he lost a zinc and it damaged all four blades so he had it redone at a prop shop. Still looks like someone tried to polish it with a grinder. I cleaned it up a little myself. I put it on my boat and took it for a ride. Got a lot less chine walk then with my chopper. Probably able to trim a little more. I had a top speed of 72mph on my phones GPS. 1 mph faster then my Chopper. And it was rough out. Not a lot of places to hold it open. I might be able to get a little more out of it on a nicer day.

[KIRCHNER]

I need a bigger prop for my Checkmate. 1989 17' Spectra 2.5 200 HP. Propshaft level with the pad. I want a prop with lots of bow lift and no stern lift. I will need a mid 30's pitch. I have always run choppers. I want a 4 blade for the stability. Any other recommendations?

30''+ pitch, thats a tall order. for real?

[skialot2]

30''+ pitch, thats a tall order. for real?

That was before I realized my tach was wrong. This RE4 is a 27P